The present invention is generally in the field of irrigation and more specifically it is concerned with a method and system for irrigation by condensation.
There is always a demand for fresh irrigation of water and there occurs particular problems in remote country areas which lack sufficient resources of fresh water and where supply and water by pipes is costly owing to extreme distances requiring substantially long pipes and power supplies for pumping stations etc.
Various solutions are provided for that purpose, such as desalination of sea water, capturing flood water, exploiting underground aquifers etc. However, these methods of supplying irrigation water have one or more of several drawbacks such as providing water at poor quality not suitable for agriculture, high cost and low efficiency high wear of equipment, dependency upon precipitation, etc.
Other arrangements provide recovering moisture from air masses, typically by various condensation methods. These arrangements are usually highly costly and of questionable efficiency. Some particular examples provide limited solutions adjacent coastal zones wherein deep ocean water at significantly low temperature may be pumped for recovering of fresh water by condensation.
Some of the prior art patents concerning recovering of fresh water from the moist in the air are the following U.S. patent: U.S. Pat Nos. 661,944, 3,498,077, 3,675,442 and 4,459,177.
It is an object of the present invention to provide an underground irrigation system for recovering water from moisture contained in the soil by condensation pipes buried in the soil at a depth corresponding with depths of roots of agriculture growth. The term underground is used to denote that the piping is received within any media suitable for agriculture growth, wherein the pipes are received within said media. In case of an artificial soil bedding this term may be understood also as in-ground, depending on the context. Herein the specification and claims, the terms ground and sod are interchangeably used to denote the growing media.
According to a first aspect of the present invention there is provided an irrigation system comprising an energized cooling system for cooling the fluid to a temperature below ground temperature, closed-loop condensation piping buried under ground surface and an energized fluid, circulating arrangement for circulating the fluid through the system, whereby propelling the cooled fluid through the piping extracts moisture from the ground by condensation over the piping, for consumption by agriculture growth in the vicinity of the piping.
The term closed-loop denoted a system wherein substantially there is no loss of fluid. Typically, the fluid is a liquid such as water and there is provided a liquid reservoir.
In order to increase overall thermal efficiency, one or more components of the system are buried under ground for reducing heat loss during hot hours of the day. In some cases it might be advantageous to provide additional cooling systems for increasing performances of the system.
Typically, die cooling system includes beat exchanger arrangements for cooling the fluid.
The system can be a so-called stand alone irrigation system, or it may be used as a co-existing system along with a conventional irrigation system, where each of the systems may be selectively used.
The fluid circulating arrangement and the cooling system may be energized by a variety of energy sources such as, solar energy supply, wind energy, electric energy (main supply, generators, etc,), hydraulic energy, biomass energy and source of natural cold water.
In order to increase the amount of liquid recovered by condensation, it is preferred to form the piping with increased section area. This is possible by forming the piping with indentations or serrated sheath surface, increasing the effective surface of the piping which is in contact with the ground.
Typically, a control system is provided for retaining a substantially constant xcex94T by regulating fluid temperature, where:
xcex94T=Tgxe2x88x92Tf
Tg =ground temperature measure at the vicinity of the piping;
Tf =fluid temperature running through the piping, and where Tf greater than 0.
The control system is utilized also for governing flow parameters and operative patterns of the irrigation system, e.g. sensing the humidity of the soil at different hours of the day in order to recover maximum condensation liquid, determining hours of the day during which the fluids in the system is at its minimal temperature, etc.
In accordance with a second aspect of the present invention there is provided a method for underground irrigation according to which a fluid is propelled at a temperature below ground temperature, through a closed piping system buried below ground surface, thereby condensing liquid over the piping sheath for consumption by agriculture growth in the vicinity of the piping.
In accordance with the irrigation method of the invention, the piping is connected to a fluid reservoir, a circulating arrangement and a cooling system for chilling the fluid.